Water pressure actuated electric switch for cable cutter

ABSTRACT

A sealed hollow capsule having inner and outer ends and a side wall contains a pair of electric contacts spaced lengthwise of the capsule, the outer end of which supports one of the contacts. the side wall has an annular groove in it reducing the thickness at that point to a thin band that is compressible to reduce its width when a predetermined pressure is exerted against the outer end of the capsule so that one contact will engage the other contact. The switch is especially suitable for closing an electric circuit connected with electrical firing means in an explosively actuated cable cutter.

United States Patent 1191 Temple 1 WATER PRESSURE ACTUATED ELECTRIC SWITCH FOR CABLE CUTTER [75] Inventor: Ernest E. Temple, Murrysville, Pa

[73] Assignee: Mine Safety Appliances Company,

Pittsburgh, Pa.

22 Filed: Mar. 7, 1973 [211 Appl. 190.; 338,995

Related U.S. Application Data [62] Division of Ser. No. 217,116, Jan. 12, 1972, Pat. No.

[52] U.S. Cl. ZOO/61.08, 200/81 R [51] Int. Cl. Htllh 35/24 [58] Field of Search..., zoo/61.08, 81 R 5 6 References Cited UNITED STATES PATENTS 2,721,913 10/1955 Kent 200/81 R x 2,787,681 4 1957 Roeser 200/81'R x Apr.2, 1974 Fowler ZOO/61.08 X Kilmer ZOO/61.08 X

Primary Examiner-George Harris Attorney, Agent, or FirmBrown, Murray, Flick & Peckham [57] ABSTRACT A sealed hollow capsule having inner and outer ends and a side wall contains a pair of electric contacts spaced lengthwise of the capsule, the outer end of which supports one of the contacts. the side wall has an annular groove in it reducing the thickness at that point to a thin band that is compressible to reduce its' width when a predetermined pressure is exerted against the outer end of the capsule so that one contact will engage the other contact. The switch is especially suitable for closing an electric circuit connected with electrical firing means in an explosively actuated cable cutter.

5 Claims, 2 Drawing Figures WATER PRESSURE ACTUATED ELECTRIC SWITCH FOR CABLE CUTTER This application is a division of my copending patent application, Ser. No. 217,116, filed Jan. 12, 1972, now US. Pat. No. 3,739,673.

There are situations in which a ship is being towed or held in position by another ship, where it is desirable to cut the tow cable immediately upon the occurrence of a nearby underwater explosion. If this is not done, the force of the explosion may cause the ships to put such tension on the cable as to cause it to break and snap back toward the ships, where it may cause damage or injury. In other situations it is desirable to lower an object through deep water by means of a'cable, and to release the cable from the object after it has reached the desired depth so that the cable can be recovered. This has been difficult to do heretofore.

It is among the objects of this invention to provide an electric switch which is closed by water pressure, which can operate a cable cutter, which will be closed by surge pressure caused by an underwater explosion, or which can be calibrated to close at a specified water depth if allowed to sink through the water.

The preferred embodiment of the invention is illustrated in the accompanying drawings, in which FIG. 1 is an enlarged vertical section of the switch; and Y FIG. 2 is a similar view, partly the switch closed.

Referring to FIG. 1 of the drawings, a pair of electric switch contacts 1 and 2 are rigidly mounted inside of a sealed capsule 3- having inner and outer ends con' nected by a side wall. The inner contact 2 may be supported by the capsule in any suitable manner, such as by an insulating plug 4 sealed in an axial opening in the inner end of the capsule. The other contact is supported by'the outer end of the capsule a predetermined distance from the inner contact. To allow this distance or gap to be adjusted, the outer end'of the capsule includes a screw 5- that supports the outer contact. By turning that screw, the gap can be adjusted. The side wall of the capsule is provided with an annular groove 6 that reduces the thickness of the wall in that area to a thin band that is easily deformed in a manner to be described presently.

The capsule-3 is mounted in an axial socket 10 in the outer end of a metal housing 11. The inner end of the capsule is encircled by a sealing ring 12. From the inner end of the socket a short passage 13 extends into an axial bore 14 in the inner end of the housing. This bore contains an insulating ring 16 engaged by a rubber flange 17 on the end of an electric cord 18 connected with a battery (not shown). In this flange the inner contact 2 is connected with one of the wires 19 in the cord. The other wire 20 is soldered to a split metal ring 21 encircling the cord between flange 1 7 and a second rubber flange 22; The ring engages the encircling housing and is pressed tightly against it by the portion of the cord inside the ring. That portion expands when the two rubber flanges are clamped tightly between insulating ring 16 and a flanged bushing 23 that is held in place by a nut 24 screwed onto the inner end of the housing. The outer contact 1 is electrically connected through the metal capsule 3 and housing 11 with the metal ring 21 and wire 20.

When this switch is submerged in water and the water pressure against the outer end of the capsule becomes in elevation, showing great enough, the water will move the outer end of the capsule inwardly to cause the thin metal band of its side wall to compress, as shown in FIG.2. The band compresses by bending radially inwardly or outwardupon itself. When this occurs, the outer contact 1 moves into engagement with the inner contact 2 to close the switch. In order to increase the effective area against which the water pressure acts, a cup-like pressure cap 26 is slidably mounted on the outer or lower end of housing 11 around the capsule. The end wall of the cap is spaced from the end of the housing, having the capsule project from the housing, or in an equivalent manner by providing the cap with a central projection small enough to enter the housing socket 10. The cap is held against the capsule by means of circumferentially spaced headed pins 27 screwed into the cap and slidably mounted in holes through a flange 28 encircling the housing and spaced from the inner or upper end of the cap. Water is prevented from entering the space between the outer end of the housing and the cap by a sealing ring 29 mounted in a groove, such as in the periphery of the housing. It will be seen that water pressure against the outer end face of the cap sufficient to overcome the resistance of the thin band in the capsulewall will push the outer end of the capsule inwardly, causing the thin band to collapse and thereby allowing the two contacts to engage each other.

Although the electric switch disclosed herein can be used for various purposes, it is especially suitable for firing an explosively actuated cable cutter. In such a case the cable cutter would carry the battery connected to electric cord 18. On the other hand,-instead of the cable cutter being provided with its own battery, the electric cord could be made much longer and be connected to a battery located above the water.

According to the provisions of the patent statutes, I

have explained the principle of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. A water pressure actuated electric switch comprising a sealed hollow capsule having inner and outer ends and a side wall,,and a pair of electric contacts in the capsule spaced lengthwise thereof, one of the contacts being supported by the outer end of the capsule, said side wall having an annular groove therein reducing the thickness of a portion of the side wall to form a thin band in the wall, and said band being compressible to reduce its width when a predetermined water pressure is exerted against said outer end of the capsule, whereby to permit said one contact to engage the other contact.

2. A switch according to claim 1, in which said capsule includes a screw secured to said one contact and threaded in and forming part of said outer end of the capsule to permit the space between said contacts to be adjusted.

3. A switch according to claim 1, including a housing containing said capsule with the outer end of the capsule projecting from the housing, and a cup-like pressure cap engaging said outer end and slidably mounted on said housing in sealing engagement therewith.

4. A switch according to claim 3, in which said housing is provided with radially projecting means spaced preferably by 3,801,759 3 4 from the cap and provided with openings parallel to the 5. A switch according to claim 3, including a sealing axis of the cap, the switch including pins slidably disposed in said openings and secured to the cap, thepins having heads normally engaging said projecting means and mounted m a groove m one of them to hold the cap against the outer end of the capsule. 5 v

ring surrounding said housing between it and the cap 

1. A water pressure actuated electric switch comprising a sealed hollow capsule having inner and outer ends and a side wall, and a pair of electric contacts in the capsule spaced lengthwise thereof, one of the contacts being supported by the outer end of the capsule, said side wall having an annular groove therein reducing the thickness of a portion of the side wall to form a thin band in the wall, and said band being compressible to reduce its width when a predetermined water pressure is exerted against said outer end of the capsule, whereby to permit said one contact to engage the other contact.
 2. A switch according to claim 1, in which said capsule includes a screw secured to said one contact and threaded in and forming part of said outer end of the capsule to permit the space between said contacts to be adjusted.
 3. A switch according to claim 1, including a housing containing said capsule with the outer end of the capsule projecting from the housing, and a cup-like pressure cap engaging said outer end and slidably mounted on said housing in sealing engagement therewith.
 4. A switch according to claim 3, in which said housing is provided with radiallY projecting means spaced from the cap and provided with openings parallel to the axis of the cap, the switch including pins slidably disposed in said openings and secured to the cap, the pins having heads normally engaging said projecting means to hold the cap against the outer end of the capsule.
 5. A switch according to claim 3, including a sealing ring surrounding said housing between it and the cap and mounted in a groove in one of them. 